Thanks all for the advice. The problem with SQ 31 is that J is sold out on 3/18. I'm currently wait-listed on that flight.

On the visa issue in PEK, I have a valid multiple-entry Chinese visa, though I doubt I could use that for transit, or if it would even speed things up.

I'll look into SQ 11 from LAX. The other itinerary they offered was PSP-SFO-NRT-SIN with NRT-SIN on ANA. 1hr 33 min connection in NRT. Seems better than PEK if there are no other options.